Missing AMD GPU firmware issue on Ubuntu 17.10

You can safely ignore those lines.

What you noticed there aren’t "errors". Instead, you’re looking at "warnings" (which you can recognize from the fact that those lines are prepended with a w).

The reason you’re seeing those warnings (and what they don’t tell you) is that all AMD graphics will now load up with llvmpipe and spit out that message (especially in development version).

Anyway, those warnings can be safely ignored.

Nota Bene: What you do not want to do is to fetch the files apt warns about from sources like people.freedesktop.org/~agd5f/radeon_ucode/raven/ as that might introduce a potential attack vector. If you embrace your personal security, don’t simply trust unknown binaries from random sources which can not be verified to be benign.